Propargylabietylamines as corrosion inhibitors in acid solutions



United States Patent 3,242,094 PROPARGYLABIETYLAMINES AS CORROSION INHIBITORS IN ACID SOLUTIONS Billy D. Oakes, Midland, Mich, assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Original application May 7, 1962, Ser. No. 192,973, new Patent No. 3,201,467. Divided and this application Aug. 17, 1964, Ser. No. 397,353

20 Claims. (Cl. 252148) This case is a division of application Serial No. 192,973, filed May 7, 1962, now Patent No. 3,201,467.

This invention relates to new compounds which are useful as corrosion inhibitors, to aqueous acids inhibited with said compounds, and to processes for making said compounds and for inhibiting the corrosion of metals exposed to aqueous acids.

The corrosion inhibitors of the invention are secondary or tertiary amines or quaternary ammonium bases or salts of such amines or ammonium bases, wherein there is at least one propargyl or 3-hydroxymethylpropargyl (4-hydroxy-2-butynyl) radical and at least one abietyl-type radical. By abietyl-type radical is meant radicals such as abietyl, dehydroabietyl, dihydroabietyl, tetrahydroabietyl and the like. Thus, the new inhibitors can be represented by the generic formula h wherein R represents an abietyl-type radical, R represents an aliphatic hydrocarbon radical containing from 1 to about 20 carbon atoms, preferably alkyl or alkenyl, A represents an anion and m, n, p, x, y and 2 represent integers, in and 2 each being 0 to 1, n and p each being 0 to 2, and x and y each being 1 to 3, the values of n, p, x, y and z being chosen such that they satisfy the equation n+p+x+yz=3.

The anion A in the above formula is ordinarily a halide ion, usually Clor Br, derived either from the corresponding acid HA or from an organic ester of such acid. Thus, in making the amine, a reactant such as RA or HOCHZCECCHZA may be condensed with an appropriate amine to produce the final product. Since when the inhibitor is added to aqueous acid the anion A, if diiferent from the anion of the aqueous acid, will be largely or completely displaced by the latter, it is apparent that the identity of A is of no real significance. As a matter of convenience it is ordinarily chloride, bromide, sulfate, phosphate, acetate or the like. It is absent, of course, in the free amines. When the amines are mixed with aqueous acids they form the corresponding salt with the acid.

The new amines and quaternary ammonium compounds can be conveniently made by the condensation of a propargyl halide or a S-hydroxymethylpropargyl halide with an abietyl-type amine. If the amine is a secondary or tertiary amine, the substituents on the nitrogen may all be abietyl-type or one may be aliphatic hydrocarbon and the others abietyl-type. Alternatively, the new amines may be made by the condensation of a propargyl-type primary or secondary amine with an abietyl-type halide. By propargyl-type amine is meant an amine containing at least one propargyl or 3-hydroxymethylpropargyl radical.

ICC

Still another method for making the new amines is to condense ammonia or a primary or secondary alkylamine successively with a propargyl-type halide and an abietyltype halide. All the foregoing amine-halide condensations can be effected by simply mixing the reactants and preferably, applying mild heat. Suitable temperatures are from room temperature to about C. When more than one mole of halide is to be condensed with ammonia or an amine it is necessary to use an equivalent of a base, such as alkali metal hydroxide or carbonate, to neutralize the hydrohalide acid that is produced. All the intermediates required in the above processes are known or can be made by obvious modifications of the methods used to make known analogous compounds.

The preparation of a typical compound of the invention is illustrated by the following example. The others were made by the substitution of the appropriate reactants in the same general procedure.

Example 1.-Preparation of N,N-dipropargylabiefylamine A suitable reactor was charged with 236.7 g. (300 ml.) of absolute ethanol, 72.8 g. (0.25 m.) of abietylamine and 50 g. (0.60 m.) of sodium bicarbonate. While the mixture was heated at reflux, 59.3 g. (0.50 m.) of propargyl bromide was slowly added over a period of 1 hour. Reflux was continued for an additional 3 hours, after which the reaction mixture was cooled and filtered. The filtrate was poured into one liter of water, whereupon the desired product separated as a lower oily layer. This was separated and dried to yield 67 g. of an oil identified by infrared spectrum as N,N-dipropargylabietylamine.

The free amines of the invention are viscous liquids, substantially insoluble in water but readily soluble in many organic solvents. The amine salts and the quaternary ammonium salts are more or less crystalline solids which are soluble or self-dispersing in water, at least in the low concentrations in which they are ordinarily used as corrosion inhibitors.

While the compounds of the invention are excellent corrosion inhibitors for aqueous acids, it has been discovered that their eifectiveness is markedly improved by the presence of a conventional surfactant. The nature of the surfactant is not important. It may be anionic, cationic or non-ionic. The non-ionics are usually somewhat more etfective, however, and are generally preferred.

Since the amines of the invention are typically very viscous, sticky liquids, the handling and measuring of the materials is greatly facilitated by the addition thereto of a minor amount of an organic diluent. Thus, the addition of 1 volume of isopropyl alcohol to 8 volumes of one of the compounds of the invention produces an enormous reduction in the viscosity of the latter and renders it readily pourable, even at temperatures as low as 18 F. The alcohol produces no appreciable effect on the corrosion inhibition of the compound. Other suitable diluents include lower alkanols, ketones, ethers and hydrocarbons.

In evaluating the new compounds as corrosion inhibitors for aqueous acid they were added to 15% aqueous hydrochloric acid and the corrosiveness of the acid on AISI 1010 mild steel determined. In these tests, a coupon of the metal measuring 1" x 2.75" x 0.12" was placed in a flask with 150 ml. of 15% aqueous hydrochloric acid and the flask was held at a constant temperature for 16 hours, after which the coupon was rinsed, dried and weighed to determine the weight loss due to corrosion. This was then calculated as lbs. per sq. ft. per day. The results of a series of such tests are shown in Table I. Examples 5 and 6 in the table show the relative ineffectiveness of propargylamine and abietylamine, respectively, these being compounds not included in the present invention.

The example in Table II show the improvement in corrosion inhibition that is produced by the inclusion of a surfactant. In these tests the procedure was the same as for Examples 2-6 except that all tests were run at 200 F. and with 0.3% by volume of N,N-dipropargylabiethylamine as the inhibitor. Surfactant concentration was 0.2% by volume.

TABLE II Corrosion Ex. N0. Surfactant Rate, lb./ sq. It./day

7 N 0.055 8 Nonylphenol condensed with 15 moles of ethyl- 011 eue oxide. 9 Ammonium isopropylbenzenesullonate 045 10 Fatty alkyl quaternary ammonium chloride 042 In a preferred embodiment of the invention it was found that the ability of the compounds of the invention to inhibit the corrosion of metal exposed to aqueous acids is markedly and unexpectedly increased by the addition thereto of a minor proportion of a 2-alkyn-1-ol containing 3 to 6 carbon atoms. This improvement is especially valuable in the protection of easily corrodable metals and/or the inhibition of acids at high temperatures; i.e., where corrosion conditions are especially severe. This feature is illustrated by the data in Table III. The tests there recorded were run in the same way as those in the preceding tables except that the metal sample was a 1- inch wide quarter-segment of 2.375-inch O.D. API N80 steel tubing, the temperature was 200 F. and the inhibitor, in addition to the alkynol, consisted of a mixture of 8 volumes of N,N-dipropar-gylabietylamine, 4 volumes of a surfactant made by condensing nonylphenol with molar equivalents of ethylene oxide, and 1 volume of isopropyl alcohol. The percentages of inhibitor shown in the table are based on the mixture rather than on the pure amine and are referred to the volume of the aqueous acid.

The elfect of concentration of inhibitor on the corrosion rate is shown by a series of experiments in which AISI 1010 steel coupons, 1" x 2.75" x 0.12, were placed in 150 ml. of 15% hydrochloric acid and held at 200 F. for 16 hours, after which the weight loss was determined as in the above tests. Two inhibitor formulations were tested. In Serial A the inhibitor was N,N-dipropargylabietylamine while in Series B it was N,N-bis(3-hydroxymethylpropargyl)abietylamine. In both series the amine was mixed with a surfactant and isopropyl alcohol in the volume ratio of 8:421, as in Examples 11-13, the surfactant being the same as was used in Examples 8 and 11-13. Results of these tests are shown in the following table.

TABLE IV Corrosion Rate, lb./sq. Concentration tt./day Ex. No. of Inhibitor,

percent by volume A B None 1. 0 1. 0 0. 4 011 013 0. 3 010 027 0. 1 032 052 05 26 Not tested TABLE V Corrosion Rate, lb. sq. it./day

Ex N0. Inhibitor The other compounds of the invention are effective corrosion inhibitors in aqueous non-oxidizing acids as is demonstrated by tests similar to those shown in the above examples. Among such compounds are N-propargyl-N- butylabietylamine, N-(3-hydroxymethylpropargyl) N octadecylabie-tylamine, N,N dipropargyl-N-octylabietylammonium bromide, N-proparagyldiabietylamine, N-(3- hydroxymethylpropargyl) N allyldihydroabietylamine, N,N dipropargyltetrahydroabietylamine, N,N-dipropargyl N oleyldihydroabietylammonium phosphate, N,N- bis(3-hydroxymethylpropargyl) N,N bis(dihydroabietyl)ammonium acetate, N,N,N-tripropargyltetrahydroabietylamrnonium sulfate, N-propargyl-N,N-bis(2-ethylhexyl)dehydroabietylammonium bromide and N-propargyltriabietylammonium chloride.

I claim:

1. An aqueous, non-oxidizing acid containing, as a corrosion inhibitor therefor, a small but effective amount of a compound having the formula wherein R represents a radical selected from the group consisting of abietyl, dehydroabietyl, dihydroabietyl and tetrahydroabietyl radicals, R' represents an aliphatic hydrocarbon radical containing 1 to about 20 carbon atoms, A represents an anion and m, n, p, x, y and z represent integers, m and z each being 0 to l, x and y each being 1 to 3, n and p each being to 2, and n, p, x, y and 1 being such that they satisfy the equation 2. An acid composition as defined in claim 1 wherein the acid is hydrochloric acid.

3. The composition defined in claim 1 comprising a minor proportion, sufficient to reduce the corrosiveness thereof, of a 2-alkyn-1-ol having 3 to 6 carbon atoms.

4. The composition of claim 3 wherein the 2-alkyn-1-ol is propynol.

5. An acid composition as defined in claim 1 wherein R represents an abietyl radical.

6. An acid composition as defined in claim wherein the inhibitor is N,N-dipropargylabietylamine.

7. An acid composition as defined in claim 5 wherein the inhibitor is N,N,N-tripropargylabietylarnmonium halide.

8. An acid composition as defined in claim 5 wherein the inhibitor is N,N-bis(3-hydroxymethylpropargyl)dehydroabietylamine.

9. A corrosion inhibitor composition for aqueous acids comprising: (1) a compound having the formula h wherein R represents a radical selected from the group consisting of abietyl, dehydroabietyl, dihydroabietyl and tetrahydroabietyl radicals, R represents an aliphatic hydrocarbon radical having 1 to 20 carbon atoms, A represents an anion and m, n, p, x, y and z represent integers, m and z each being 0 to 1, x and each being 1 to 3, n and p each being 0 to 2, and n, p, x, y and 2 being such that they satisfy the equation n+p+x+y-z=3,

and (2) a minor proportion, sufficient to improve the (1) is N,N dipropargylabietylamine and component (2) is hexynol.

12. The process for inhibiting the corrosiveness of aqueous acids toward ferrous metal in contact therewith comprising maintaining in said acid a small but effective concentration of a corrosion inhibitor having the formula H [H(CHOH)m-CE(JCHz]xN(H)n-(A),

wherein R represents a radical selected from the group consisting of abietyl, dehydroabietyl, dihydroabietyl and tetrahydroabietyl radicals, R represents an aliphatic hydrocarbon radical having 1 to about 20 carbon atoms, A represents an anion and m, n, p, x, y and z represent integers, m and z each being 0 to l, x and y each being 1 to 3, n and p each being 0 to 2, and n, p, x, y and z being such that they satisfy the equation 13. The process defined in claim 12 wherein the corrosion inhibitor comprises a minor proportion, sufiicient to improve the corrosion inhibition properties thereof, of a 2-alkyn-1-ol having 3 to 6 carbon atoms.

14. The process of claim 13 wherein the 2-alkyn-1-ol is propynol.

15. The process defined in claim 12 wherein R represents an abietyl radical.

16. The process defined in claim 15 wherein the inhibitor is N,N-dipropargylabietylamine.

17. The process defined in claim 15 wherein the inhibitor is N,N,N-tripropargylabietylammonium halide.

18. The process defined in claim 15 wherein the inhibitor is N,N bis(3 hydroxymethylpropargyl)dehydroabietylamine.

19. The process of claim 12 wherein the acid is hydrochloric acid.

20. The process for inhibiting the corrosiveness of hydrochloric acid toward ferrous metal in contact therewith comprising maintaining in the acid about 0.05 to 1% by volume of N,N-dipropargylabietylamine.

References Cited by the Examiner UNITED STATES PATENTS JULIUS GREENWALD, Primary Examiner. 

1. AN AQUEOUS, NON-OXIDIZING ACID CONTAINING AS A CORROSION INHIBITOR THEREFOR, A SMALL BUT EFFECTIVE AMOUNT OF A COMPOUND HAVING THE FORMULA 